<template>
  <div class="goods">
    <div class="menu-wrapper" ref="menuWrapper">
      <ul>
        <li
          v-for="(item, index) in this.goods"
          class="menu-item border-bottom"
          :class="{'current': currentIndex === index}"
          @click="selectMenu(index, $event)"
          ref="menuList"
        >
          <span class="text">
            <span
              v-show="item.type > 0"
              class="icon"
              :class="classMap[item.type]"
            ></span>
            {{item.name}}
          </span>
        </li>
      </ul>
    </div>
    <div class="foods-wrapper" ref="foodsWrapper">
      <ul>
        <li
          v-for="(item, index) in goods"
          :key=index
          class="food-list-hook"
        >
          <h1 class="title">{{item.name}}</h1>
          <ul>
            <li
              v-for="(food, ind) in item.foods"
              :key=ind
              class="food-item border-bottom"
              @click="selectedFood(food, $event)"
            >
              <div class="icon">
                <img width="57" height="57" :src="food.icon" />
              </div>
              <div class="content">
                <h2 class="name">{{food.name}}</h2>
                <p class="desc">{{food.description}}</p>
                <div class="extra">
                  <span class="count">月售{{food.sellCount}}份</span><span>好评率{{food.rating}}%</span>
                </div>
                <div class="price">
                  <span class="now">￥{{food.price}}</span>
                  <span v-show="food.oldPrice" class="old">￥{{food.oldPrice}}</span>
                </div>
                <div class="cartcontrol-wrapper">
                  <CartControl :food="food"
                    ></CartControl>
                </div>
              </div>
            </li>
          </ul>
        </li>
      </ul>
    </div>
    <food :food="selFood" ref="food"></food>
  </div>
</template>

<script>
import BScroll from 'better-scroll'
import CartControl from './common/CartControl'
import food from '_c/food'
import { mapState, mapMutations, mapActions, mapGetters } from 'vuex'
export default {
  name: 'Goods',
  components: {
    CartControl,
    food
  },
  data () {
    return {
      listHeight: [],
      scorllY: 0,
      selFood: {}
    }
  },
  created () {
    this.classMap = ['decrease', 'discount', 'special', 'invoice', 'guarantee']
  },
  mounted () {
    this._initScroll()
    this._calculateHeight()
  },
  computed: {
    ...mapState(['goods']),
    currentIndex () {   // currentIndex === index 为true，class生效
      for (let i = 0; i < this.listHeight.length; i++) {
        let height1 = this.listHeight[i]
        let height2 = this.listHeight[i+1]
        if (!height2 || (this.scorllY >= height1 && this.scorllY < height2)) { // 如果最后一个height不存在，直接返回i
          return i
        }
      }
    }
  },
  methods: {
    _initScroll () {
      this.menuScroll = new BScroll(this.$refs.menuWrapper, {
        click: true  // 开启点击事件（BS默认会阻止掉）
      })
      this.foodsScroll = new BScroll(this.$refs.foodsWrapper, {
        click: true,
        probeType: 3  // 设定BS 实时监测滚动位置
      })
      this.foodsScroll.on('scroll', (pos) => {  // 这里要用箭头函数绑定this
        // 判断滑动方向，避免下拉时分类高亮错误（如第一分类商品数量为1时，下拉使得第二分类高亮）
        if (pos.y <= 0) {
          this.scorllY = Math.abs(Math.round(pos.y))
        }
      })
    },
    _calculateHeight () {
      let foodList = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook')   // 每个foodlist的高度就是每个区块的高度
      let height = 0
      this.listHeight.push(height)
      for (let i = 0; i < foodList.length; i++) {
        let item = foodList[i]
        height += item.clientHeight   // clientHeight 每个区块的可视高度
        this.listHeight.push(height)
      }
    },
    _followScroll (index) {
      let menuList = this.$refs.menuList
      let el = menuList[index]
      this.meunScroll.scrollToElement(el, 300)
    },
    selectMenu (index, event) {
      if (!event._constructed) {
        return
      }
      let foodList = this.$refs.foodsWrapper.getElementsByClassName('food-list-hook')
      let ele = foodList[index]
      this.foodsScroll.scrollToElement(ele, 300)  // BS接口，滚动至
    },
    selectedFood (food, event) {
      if (!event._constructed) {
        return
      }
      this.selFood = food
      this.$refs.food.show()
    }
  }
}
</script>

<style lang="stylus" scoped>
@import '~styles/mixin.styl'
.goods
  display flex
  position absolute
  top 174px
  bottom 46px
  width 100%
  overflow hidden
  .menu-wrapper
    flex 0 0 80px
    width 80px
    background #f3f5f7
    .menu-item
      display table
      padding 0 12px
      height 54px
      width 56px
      line-height 14px
      &.current
        margin-top -1px
        background #fff
        font-weight 700
      .text
        display table-cell
        width 56px
        vertical-align middle
        font-size 12px
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
          &.decrease
            bg-image('~img/goods/decrease_3')
          &.discount
            bg-image('~img/goods/discount_3')
          &.guarantee
            bg-image('~img/goods/guarantee_3')
          &.invoice
            bg-image('~img/goods/invoice_3')
          &.special
            bg-image('~img/goods/special_3')
  .foods-wrapper
    flex 1
    .title
      padding 14px
      border-left 2px solid #d9ddel
      height 26px
      line-height 26px
      font-size 12px
      color rgb(147,153,159)
      background #f3f5f7
    .food-item
      position relative
      display flex
      margin 18px
      padding-bottom 18px
      &:last-child
        border-none()
        margin-bottom 0
      .icon
        flex 0 0 57px
        margin-right 10px
      .content
        flex 1
        .name
          margin 2px 0 8px 0
          height 14px
          line-height 14px
          font-size 14px
          color rgb(7,17,27)
        .desc, .extra
          line-height 10px
          font-size 10px
          color rgb(147,153,159)
        .desc
          margin-bottom 8px
          line-height 12px
        .extra
          .count
            margin-right 12px
        .price
          font-weight 700
          line-height 24px
          .now
            margin-right 8px
            font-size 14px
            color rgb(240,20,20)
          .old
            text-decoration line-through
            font-size 10px
            color rgb(147,153,159)
        .cartcontrol-wrapper
          position absolute
          right 0
          bottom 12px
</style>
